The assessment scans will be reviewed by Independent Review Committee (IRC). At any time when PD is observed, the patient will be removed from further study treatment; any further treatment will be at the discretion of the investigator. Melphalan/HDS treatment will also be discontinued in the event that recovery requires more than 8 weeks from last treatment. An end-of-treatment visit will be conducted approximately 6 to 8 weeks following the final dose of study treatment. Ongoing adverse events (AEs) at the end-of-treatment visit will be followed until the severity returns to common terminology criteria for adverse events (CTCAE) Grade < 1.